External Parasites Lice and Ticks

Rhipicephalus sanguineus

Brown dog tick, kennel tick

Adult onset demodicosis

Cancer or internal disease in adult dogs create an immune suppressed environment for mites to rapidly multiply

Otobius spp.

spinose ear tick

Cheyletiella

walking dandruff mite, live on surface of skin found dorsal back both cats and dogs saddled shaped body, 2 pairs legs front and back, hooks next to the mouth zoonotic treated with insecticide

Demodicosis

when an animals immune response is immature or becomes compromised these mites increase in numbers resulting in skin disease can cause moderate to severe hair loss, thickening of skin and 2ndary skin infection animal w/ demodicosis do not have pruritus/itching 2 primary forms; local and generalized demodicosis

Lice; Life Cycle, Healthy/Sick Dogs, Features

- Life cycle takes 3 wks, features incomplete metamorphosis (each stage looks like previous stage). - While rare on healthy animals, poorly nourished dogs may have heavy infestations, adding to their troubles. - Clinical features include pruritis, scaling, scabby skin, seborrhea sicca (dandruff), loss hair, in severe cases secondary bacterial infection. Heavy infestations may lead to anemia

Hard Ticks - Life Style 1, 2, 3 host ticks

- 1 host tick: the entire development from larva to adult takes place on 1 host. - 2 host tick: the larva and nymph occur on 1 host and the adult on another. - 3 host tick: each stage of development, larva, nymph and adult takes place on a different host. The life cycle can take as long as 3yrs to complete.

Hard Ticks - Life Cycle

- 3 distinct life stages which completed 1, 2, or 3 hosts. - All ticks feature a larval (seed tick), nymphal, and adult stage. Both immature stages look similar to adult stage. - Larvae emerge from eggs w/ 6 legs. After engorging on blood from a vertebrate host (usually a small rodent), they drop off and molt to the nymphal stage and acquire 8 legs. - Nymphs engorge, drop off, and molt to the next and final stage - the adult, which also has 8 legs. - After feeding once more, the adult female hard ticks lay 1 batch of thousands of eggs and then die.

Hard Tick - Species ; Brown Dog Tick or Kennel Tick (Rhipicephalus Sanguineus)

- 3 host tick that is important pest of dogs in the U.S., especially those housed in kennels. It feeds on dogs during all 3 life stages, but drops off and reattaches during each stage. Unlike most other hard ticks, eggs of this tick are laid inside/near housing areas of animals, in cracks and crevices, rather than outside, on the ground under vegetation. This tick is the vector of canine ehrlichiosis rickettsia and canine babesiosis protozoa in the U.S.

Hard Tick - Species ; American Dog Tick (Dermacentor Variabilis)

- 3-host hard tick common in deciduous forests of the Eastern U.S. and along the West Coast. Most common vector of Rocky Mountain spotted fever in the eastern US, which tick can transmit after only 5-20hrs of feeding. Toxins found in the saliva of the American dog tick, which are injected during feeding, are the causative agents of tick paralysis in dogs.

Hard Ticks - Species ; Deer Tick (Ixodes Scapularis)

- 3-host hard tick found across U.S. wherever its preferred adult host, deer, are found. Gained particular attention as most important vector of Lyme disease. - Must feed 24hrs to transmit Lyme disease. Lyme disease is caused by the spirochete, Borrelia burgdorferi which is a corkscrew-shaped bacteria. Its primary wild reservoir is the white-footed mouse which infected by spring-feeding, pathogen- infected blacklegged/deer tick nymphs. - These white-footed mice then serve to infest the later-feeding blacklegged/deer tick larvae, which keeps the disease cycle going. Tick eggs don't contain the spirochete, so it is acquired via feeding.

Ticks - General Facts

- 8-legged, blood-feeding ectoparasites closely related to spiders, scorpions, mites and live on mammals and birds. 800 different species of ticks. - Ticks are large (compared to fleas and mites). Unlike fleas, all parasitic stages of the tick (larvae, nymph, adult) may feed on pets. Ticks can consume 200-600x their body weight in blood. - Most ticks attach to host and feed for 12-24 hrs before they fall off. Young ticks (nymphs) may feed on 1 host, drop off, then feed on a different host as adults. Most ticks spend about 10% of their lifetime attached to their hosts. The adults of common hard ticks can live for months off the host; some up to 2yrs. (Female ticks engorge w/ blood, male ticks bite-but engorge w/ blood. Males transmit disease, since they bite.)

Tick - Borne Diseases

- Apart from irritation/anemia in case heavy infestations, ticks cause severe dermatitis, even w/ 2ndary infections which result in high mortality. When tick-borne diseases (TBD's) are mentioned, refers to blood parasites. - Many tick-borne pathogens remain in the tick when it molts from 1 stage to next, e.g., Ehrlichia canis in Rhipocephalus sanguineous, and Borrelia burgdorferi in Ixodes scapularis. This is called transtadial/horizontal transmission. - 1 host ticks and some 3 host ticks exhibit transovarian* transmission of pathogens, i.e., they infect the ovaries of the tick and pass with the eggs to the next generation of ticks, e.g., the rickettsia of Rocky Mountain spotted fever in Dermacentor andersoni and D. variabilis. - #2 to mosquitos

Soft Ticks (Argas spp.) (Otobious spp.)

- Argas the Fowl Tick, affect wild and domesticated birds, occasionally man. Eggs laid in batches of 25-100 in crevices in poultry houses/under the bark of trees. Their presence is annoyance, decreased egg production. Anemia seen in heavy infestations. Is also a cause of tick paralysis. - Otobius megnini is th spinose ear tick and most common soft-bodied ticks. 2 larval stages of this tick feed in the external ear canal of host and subsequently drop to the ground. Adult ticks do not have functional mouthparts and do not feed. Infestation has been reported in a variety of domestic and wild mammals, including cattle, horses, sheep, cats, dogs. Larval stages pear-shaped to spherical in shape. The cuticle is covered by spines and mouthparts are not readily visible on the dorsum.

Tick Removal Procedure

- Avoid handling ticks w/ uncovered fingers; use tweezers/commercial tools designed for removal. If index finger and thumb must be used, protect them w/ rubber/plastic gloves. - Place tips of tweezers/edges of other removal devices around the area where the mouthparts enter the skin. - steady slow motion, pull tick away from skin/slide the removal device along the skin (read directions for each commercial tool). Do not jerk, crush, squeeze, puncture the tick. - After removal, place tick directly into sealable container and retained at least a month. - Disinfect the area around the bite site using standard procedures. Watch for the development of possible tick-borne diseases

Tick Paralysis (Tick-Bite Paralysis) ; Clinical Features, Diagnosis, Treatment and Control

- Clinical Features: Temp. usually normal. there are discomfort and vomiting and dysphagia. Abnormal fore- and hindlimb reflexes, unsteady gait, incoordination and weakness w/ ascending paralysis. Sensation and consciousness is retained. In few hrs the animal is unable to move, breathing is difficult and death may ensue in several hrs if ticks are not removed. If ticks are removed in time recovery takes place within 1 - 3 days. - Diagnosis: Based on the progressive paralysis and the presence of ticks. Rapid recovery after tick removal is confirmatory. There are no observable lesions and blood and fluid values are normal. - Treatment and Control: None, other than prompt removal of ticks. Measures should be directed toward reducing exposure to ticks and removal when present.

Lice; Diagnosis, Treatment, Control

- Diagnosis: Lice are 2-4 mm size and seen moving on animal w/ the naked eye. Sucking lice move more slowly than biting lice - Treatment: Most flea preparations readily kill lice. They can be employed as powder, shampoo/dip. To destroy hatching eggs treatment should be applied wkly for least 5 wks. - Control: Destroy infected bedding. Thoroughly vacuum carpets and clean (wash) floors. Frequent grooming w/ removal of eggs. - wkly/biwkly for 30days

Sucking Lice

- Feed on their host's blood and unable to survive away from their host for more than 24-36 hrs. Sucking lice will leave a dead host, or one that has a high fever for a more suitable host and this is a crucial factor in transmission of pathogens through livestock herds.

Biting Lice Felicola Surostrata

- Felicola Surostrata only louse that occurs on cats. Louse is minor importance, found in large numbers only on elderly or sick cats especially if they are long-haired.

Hard Ticks - Life Cycle ; Questing

- Hard ticks seek hosts by interesting behavior called "questing." - Questing ticks crawl up stems of grass/perch on edges of leaves on the ground in a typical posture w/ front legs extended, especially in response to a host passing by. - Subsequently, these ticks climb on to a potential host which brushes against their extended front legs.

Tick Paralysis (Tick-Bite Paralysis) ; Immunity, Public Health Significance

- Immunity: Dogs and cats that live in areas regularly pick up ticks tend to develop immunity. depends on them getting small doses of tick toxin initially, not enough to cause severe illness, but enough to start production of antibodies by animal's immune system. As they pick up more ticks and injected by gradually increasing doses of toxin this immunity can become quite strong. Unfortunately this immunity is not long lasting and can be lost from 1 season to next if there are no ticks on animal in time between. A previously immune dog can suddenly become affected by tick paralysis. - Public Health Significance: Humans are susceptible to tick paralysis initiated by tick bites; however, animals w/ tick paralysis cannot transmit the disease to humans.

Lice Types

- Lice are wingless, flattened insects that are ectoparasites of warm-blooded animals worldwide. - There are 2 basic types of lice: biting lice (Order Mallophaga), sucking lice (Order Anoplura)

Causes of lice Infestation

- Major causes of pediculosis (lice infestation) in domestic animals include: > Tricodectes canis - Dog; biting louse. >Felicola surostratus - Cat; biting louse. > Damalina equis - Horse; biting louse >Hematopinus suis - Pig; sucking louse > Linognathous setosus - Dog; sucking louse - Small insects divided into 2 categories; biting lice (mallophagia), sucking lice (anoplura) - Diagnosis; piece of scotch tape pressed directly onto skin where lice is suspected, transfer tape onto microscopic slide, low power. > this technique also helps examine flea eggs, cheyletiella, other small skin mites

Mallophaga spp. (biting lice) vs. Anoplura spp. (Sucking Lice)

- Mallophaga spp. (biting lice) (A) differs from Anoplura spp. (sucking lice) (B) in their general body morphology. - Sucking lice tend to be slightly larger than biting lice, have small heads in relation to body size. (blood feeders) - Lice are extremely host specific, w/ particular lice species found on only 1 host species. Some lice have found on different hosts but generally closely related, such as sheep and goats.

Tick Paralysis (Tick-Bite Paralysis)

- More than 20 species of ticks w/ varying geographic distribution been reported to have the capacity to produce tick paralysis. This condition mainly affects humans (children especially), dogs, and cats. to be due to a protein neurotoxin produced by ticks and introduced during biting. Those mainly involved in North America are D. variabilis and D. andersoni. Young animals are most susceptible to tick paralysis. - Toxicity: The circulating neurotoxin interfers w/ acetylcholine release at neuromuscular junctions leading to ascending paralysis. Toxicity is mainly w/ female ixodid ticks and incidence of the disease is related to the latter's activity in the spring and early summer. The incubation period is 5-9days, i.e., from time of introduction of toxin until signs appear. It generally takes several ticks to cause paralysis, however, one tick strategically located near the base of the skull or spine can result in symptoms

Lice

- Phylum Arthropoda > Class Insecta ** Order Mallophaga (biting or chewing lice) >>> Damalinia equi, Trichodectes canis, Felicola subrostata ** Order Anoplura (sucking lice) >>> Haematopinus suis, Linonathus setosus

Tick - Species Ixodidae (hard ticks) and Argasidae (soft ticks)

- Species; small number of species of 2 of the 3 families of ticks, Ixodidae (hard ticks) and Argasidae (soft ticks) parasitize dogs and cats - Members of the family Ixodidae are the most common ticks found on dogs, cats and other domestic animals. These are commonly referred to as "hard ticks" because they possess a scutum/shield. Shield covers the entire back of the male and part upper back of the female tick. The shield prevents expansion of the covered portion during engorgement. - Although Ixodiade and Argasidae share some basic features, they differ in many others including morphologic, physiologic, feeding habits and reproductive patterns. - Both families feature some species which are ornate. "Ornate" ticks have a colored enamel-like area covering the body.

Parasitology Taxonomy

- Subphylum Chelicerata, Class Arachnida > Order Acari ** Suborder Metastigmata >>> Family Ixodidae (hard ticks) **** Amblyomma americanum (lone star tick), Dermacentor varabilis (american dog tick), Dermacentor andersoni (Rocky Mountain Wood tick), Ixodes scapularis (deer tick), Rhipicephalus sanguineus (brown dog tick) >>> Family Argasidae (soft ticks) **** Argas (the fowl tick), Otobius megnini

Sucking Lice Hematopinus Suis

- The hog louse, the largest louse species (4-6mm) associated w/ domestic animals. found most frequently in folds of skin behind ears and between legs. The blood-sucking activity of hog lice results in much irritation and discomfort to swine. - Eggs are glued to bristles at the rate of 3-6per female per day. The louse causes severe irritation resulting in a depressed growth rate.

Biting Lice (Trichodectes Canis)

- The louse species most commonly feeds on domestic dogs, other canids such as coyotes, wolves, foxes, may come into contact w/ dogs. Unlike ticks and other parasites, are very host-specific. - Trichodectes canis is 1.5 mm in length w/ dorsoventrally flattened body and a broad, flat head. Each of 6 legs (3 pairs) armed w/ a strong claw for holding onto the host canid, even in the face of frantic biting and scratching. - Trichodectes canis can act as the intermediate host for the dog tapeworm, Dipylidium caninum. - Result in alopecia and hair loss, harder to catch

Sucking Lice Linognathus Setosus

- The only sucking louse in dogs of any importance.

Human Lice - FYI ; Head, Pubic (Crab), Body Lice

- There are three types of human lice: head lice, pubic (crab) lice, and body lice. They are all transmitted by close body contact w/ infested person/contact w/ shared items like clothing, bedding, combs, brushes, even toilet seats. They do not, jump from person to person lice bite the skin and feed blood, this causes the characteristic itching. - Head lice: Kids up to 12 are usually affected, but their parents/other family contacts also at risk. Frequent scratching of scalp usually leads to inspection by an adult and classic findings of nits (lice eggs). Nits are white and tear-drop shaped, seemingly glued to hair shafts near the scalp visible to naked eye - Pubic (crab) lice: Crab-like appearance, slightly larger than head lice. Many people think they are specs of dirt until they move! Crab lice are found in other hairy areas, too: underarms, eyebrows and lashes, and facial hair. - Body lice: prefer to live in clothing, travel to the skin surface only to feed before going back. Can't find them until you look at clothing (especially seams) for nits/lice.

Hard Ticks - Species ; Lone Star Tick (Amblyomma Americanum)

- This aggressive ornate hard tick is found throughout southeastern 1/3 of U.S., the eastern U.S. as far north as Rhode Island, and parts of Plains. Is 1 of most common human-attacking ticks in this region. Its role as a vector of disease in dogs and man is minimal, w/ infrequent transmission of Rocky Mountain Spotted Fever, Tularemia, and tick paralysis. Extra care should be taken when removing these ticks because that have longer hypostomes which often break off and remain in the skin causing infection

Tick Removal

- Tick's mouthparts have reverse harpoon-like barbs, designed to penetrate and attach to skin. Ticks secrete a cement-like substance that helps adhere firmly to the host. Improper removal of a tick results in part of the mouthparts remaining embedded and causing inflammation. It is important to remove it properly. - Timely removal is critical for avoiding tick-transmitted diseases by reducing the interval for pathogen entrance into the host. Folklore remedies, such as the use of petroleum jelly, ether, finger polish/hot matches, encourage a tick to detach from skin. they may make matters worse by irritating the tick and stimulating it to release additional saliva or regurgitate gut contents, increasing the chances of transmitting the pathogen. - A number of tick removal devices have been marketed, but many veterinarians and MD feel none are better than a plain set of fine tipped tweezers.

Tick - General Facts; Clinical Features

- Ticks found more commonly on dogs than cats. most common sites of infestation are the head, neck, ears, the less accessible areas for scratching and grooming. - Individual tick bites cause local reactions, including skin damage, irritation (pyoderma), inflammation, hypersensitivity. large number of tick bites can cause anemia. Some ticks secrete toxic saliva that can cause paralysis. All ticks can carry and transmit disease. Ticks are 2nd only to mosquitoes as vectors of disease.

Ticks - General Facts ; Acariasis

- Ticks of same species excrete pheromones that help locate each other on the host (this is why ticks are often found feeding in groups). female tick lay up to 20,000 eggs in single mass. Just prior to mating, detaching, female ticks consume large volume of blood, which is why ticks seem to "suddenly" appear on the dog. Infestation with ticks (or mites) is called acariasis.

Tick - Borne Diseases ; Canine Ehrlichiosis (Tick-Borne Fever)

- caused by Ehrlichia canis and spread by the brown dog tick Rhipicephalus sanguineus. occurs throughout the U.S., most common in the Southeast. The organism can pass transtadially from tick stage to tick stage. - Ehrlichiosis damages and decreases production of blood cells and leads to anemia and thrombocytopenia, lowered disease resistance, and abnormal bleeding. Diagnosis is usually based on a blood test. - Treatment involves antibiotics (tetracycline and melarsomine) and supportive care. Though the prognosis is usually good, ehrlichiosis can be fatal

Tick - Borne Diseases ; Lyme Disease (Lyme Borreliosis)

- caused by bacteria Borrelia burgdorferi and spread by the deer tick (Ixodes scapularis). - 1 most common tick-transmitted vet diseases in the world. Lyme disease can affect cats, dogs (and humans). - most common clinical symptoms of Lyme Disease are arthritis, lameness, anorexia, and depression. It can also cause cardiac, neurological, and kidney disease.

Tick - Borne Diseases ; Rocky Mountain Spotted Fever

- caused by bacteria Rickettsia rickettsii and spread by the American dog tick (Dermacentor varabilis) and wood tick (D. andersoni). The organism can pass transovarian to infect eggs of next generation of ticks. - Symptoms include fever, lethargy, depression, anorexia, swelling, a stiff gait, abnormal bleeding, breathing problems, and eye pain. Rocky mountain spotted fever is difficult to differentiate from canine ehrlichiosis. - The prognosis is good if the dog receives prompt treatment, including antibiotics and supportive care.

Hard Tick - Species ; Rocky Mountain Wood Tick - Dermacentor Andersoni)

- common name comes from primary distribution being in the Rocky Mountain states and the preferred habitat being the woods to meadow/lawn transition zone. - primary vector of Rocky Mountain Spotted Fever in the Rocky mountain states which transmit from small animals, primarily rodents. This is severe, acute, infectious disease of small peripheral blood vessels caused by rickettsiae organism whose characteristic symptom is a rash develops in 2-5days, starting w/ the wrists, ankles and then spreads over the body. Mortality in humans is 20% or more. Fortunately, attachment for 2 hrs or more is required for transmission.

Heavy Lice

- infections occur predominantly on young/old animals. Those in poor health due to either disease or bad maintenance are also prone to heavy infestations.

Biting Lice (Damalinia Equi)

- infest horses. feeds on the most superficial layers of skin and exudate which results from irritant effect of the parasite. - cause little harm and only occur in small numbers but if large infestations develop damage may occur through heavy grooming by the host. - The lateral distribution of lice over the body is influenced principally by the type of hair and skin temp. If the hair is too wide to be held by the females no eggs are laid, and thus the eggs of Damalinia are found only on the thin hairs of the body.

Biting Lice

- known as chewing lice, are not blood feeders. They feed on superficial skin, dead skin, and fragments of hair or feathers. - found on mammals and birds the majority are found on birds.

Soft Ticks

- lack the hard scutum of hard ticks. it is not possible to see their mouthparts when viewed from above. - 2 important soft tick species in domestic animals: Argas and Otobius. - life stages of soft ticks are not readily distinguishable. The first life stage to come out of the egg, a 6 legged larva, takes a blood meal from a host, molts to the 1st nymphal stage. Unlike hard ticks, many soft ticks go through multiple nymphal stages, gradually increasing in size until the final molt to the adult stage. Some soft ticks pass through up to 7 nymphal molts before become adults. Soft ticks feed several times during each life stage, females lay multiple small batches of eggs between blood meals during their lives. The time to completion of entire life cycle is generally much longer than that of hard ticks, lasting over several yrs. Many soft ticks have uncanny resistance to starvation, and can survive for many years without a blood meal.

Localized Demodicosis

affects small areas on the face/forelimbs occur in animals 3-6m in age generally resolves in time as the immune system matures

Parasite

any organism that lives on or in an organism of another species, from the body which obtains nutriment without contributing to the well being of the organism

Sarcoptic mange mite (Scabies)

burrow under the skin cause pruritus/itching found ears, elbows, belly, chest, legs, alopecia, reddish coloration, lesions yellow crust cats; ears, face, neck 15 - 20 scrapings zoonotic treat w/ paramite or mitaban dips 2 - 3wks

Mitaban

demodicosis treatment w/ this dip every 2 wks until mites no longer found in skin scraping

Amblyomma americanum

lone star tick

demodectic pododermatitis

mites concentrate on the paws of a adult dog

Generalized Demodicosis

occurs w/ localized demodicosis does not resolve on its own starts as local lesions and spreads resulting in chronic skin infections, lesions, follicular disease